I know this is out of question now, since there's a new Eeveelution, and we saw what we saw in the trailer, but... my answer would be "none of them".

A major part of what I loved about B1/W1 was the fact that all Pokémon we encountered before the National Dex were brand new. During the main campaign, I really felt like I was playing Pokémon for the first time again. I really hoped they would do the same for Gen 6.